1. Field of the Invention
The present invention relates to a brake control apparatus for automatically braking a vehicle.
2. Related Background Art
An example of a known brake control apparatus for automatically braking the vehicle is one described in Japanese Laid-open Patent Application No. 9-11870. The control apparatus described in the application No. 9-11870 is arranged to detect a leading car or an obstacle ahead of the vehicle and automatically brake the vehicle when a collision is predicted, thereby assuring a following distance and avoiding the collision.
In the control apparatus for carrying out the automatic braking as described above, a braking operation during anomalies, e.g., canceling of the automatic braking, has to be carried out when the automatic braking condition is abnormal. Prior thereto, it is necessary to detect whether the automatic braking condition is normal or abnormal.
There is a need therefore for a brake control apparatus capable of carrying out the automatic braking surely and readily detecting whether the automatic braking condition is normal or abnormal.
According to the present invention, the brake control apparatus for a vehicle comprises: (A) a radar provided on the vehicle; (B) a braking system for the vehicle; (C) a sensor that detects a physical value, the physical value being changeable as a result of action by the braking system; and (D) an electronic control unit that automatically controls the braking system based on a signal from the radar, and that automatically controls the braking system so as to cause the physical value detected by the sensor to be a predetermined target physical value, the predetermined target physical value being variable during a braking period caused by the action of the braking system, the predetermined target physical value in an initial stage of the braking period increasing with time and the predetermined target physical value in a latter stage of the braking period decreasing with time. According to this apparatus, the apparatus can detect whether the automatic braking condition is normal or abnormal when comparing the detected physical value and the predetermined target physical value.
The sensor may be a pressure sensor for detecting the brake fluid pressure in a wheel cylinder of the vehicle.
Alternatively, the sensor may be a vehicle deceleration detection sensor for detecting a deceleration in the longitudinal motion of the vehicle.
The present invention will be more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only and are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from this detailed description.